Luminescent cover

ABSTRACT

An electrophotographic printing machine in which a platen cover is arranged to illuminate a transparent platen with an original document mounted thereon. The light rays illuminating the marginal portions of the platen extending beyond the original document are transmitted therethrough discharging the photoconductor in those regions. This prevents the development of unwanted border regions on the copy paper.

United States, Patent 1 91 Kidd 1 1 LUMINESCENT COVER [75] Inventor: Wayne L. Kidd, Fairport, NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: 13, 1972 [21] Appl. No.: 298,720

52 us. c1 355/3 R, 355/7, 355/14, 355/67, 355/69, 355/113, 355/120, 240/225 51 Int. Cl ..G03g 15/00 [58] Field of Search..... 355/3, 7, 14, 17, 24, 67, 69, 355/78, 82, 113l21, 122, 128, 132, 133; 240/2.25, 22, 1.3

[56] References Cited UNITED STATES. PATENTS 3,119,317 l/1964 Cooper, Jr. et al 240/222 X 2,674,933 4/1954 Wigglesworth 355/113 3,410,190 11/1968 Browning 355/82 X [11] 3,788,737 1 Jan. 29, 1974 3,288,047 ll/l966 Limberger .l 355/100 3,238,859 3/1966 Mauchly 355/82 3,687,538 8/1972 Matsumoto 355/3 FOREIGN PATENTS OR APPLICATIONS 710,477 5/1965 Canada 240/225 Primary Examiner-Richard M. Sheen Attorney, Agent, or FirmJames J. Ralabate et al.

[ 5 7] ABSTRACT An electrophotographic printing machine in which a platen cover is arranged to illuminate a transparent platen with an original document mounted thereon. The light rays illuminating the marginal portions of the platen extending beyond the original document are transmitted therethrough discharging the photoconductor in those regions. This prevents the development of unwanted border regions on the copy paper.

6 Claims, 4 Drawing Figures PATENTEUJM 2 9 1974 SHEET 1 OF 2 FIG. I

PATENTEDJAR 2 9 191-;

SHEU 2 OF 2 LUMINESCENT COVER BACKGROUND OF THE INVENTION This invention relates generally to an electrophotographic printing machine, and more particularly concerns an apparatus for housing an original document therein.

Generally, electrophotographic printing machines are provided with a transparent platen upon which the original document is supported. An optical image of the original document is created and recorded as an electrostatic latent image upon a photoconductive surface. The machine is usually provided with a cover to prevent extraneous light from entering the optical system during the imaging process and to reflect light rays through the machine optical system preventing development of the border regions extending beyond the original document. Typically, the cover has a rigid outer shell with a suitable light weight rubber material adhering thereto and arranged to engage the original document. The rubber material is flexible and colored white to reflect light rays therefrom. US. Pat. No. 3,642,371 issued to Jones et al. in 1972, discloses a platen cover having a white reflective surface thereon. However, it has been found that platen covers of this type frequently do not reflect light rays through the transparent platen when the original document is a book or other thick member. In such situations, the platen cover cannot close entirely and the light rays from the illuminating system within the printing machine are not reflected back through the transparent platen. Hence, the light raysfail to discharge the border regions surrounding the latent image recorded on the photoconductive surface resulting in the development thereof. In this manner, a conventional black and white copier will produce a copy .having the original material thereon, but also, including frequently, a black or darkened border region resulting from the development thereof.

This is particularly significant in the case of a multicolor copy, the quality of which is, in part, related to the area surrounding the subject matter being reproduced. In a colored reproduction, border development results in the deposition of colored toner particles thereon. These border areas surrounding the copy would normally be void of color enhancing the contrast between the copy and the surrounding area.

Accordingly, it is a primary object of the present invention to improve the cover of an electrophotographic printing machine such that toner development in border areas is minimized.

SUMMARY OF THE INVENTION Briefly stated, and in accordance with the present invention, there is provided an apparatus for housing an original document.

This is accomplished in the present instance by a support member, a cover member, and illuminating means. The support member is arranged to hold the original document thereon. The cover member is operatively associated with the support member. During operation, the cover member is movable from an opened position to a closed position. In the opened position, the original document may be placed on or removed from the support member. While in the closed position, the original document is secured 'releasably on thesupport mem- 2 ber. Also in accordance with the present invention illuminating means are affixed to the cover member. The original document is disposed upon the support member and arranged such that the illuminating means is in contact therewith.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIG. l is a schematic perspective view of an electrophotographic printing machine having the present invention therein;

FIG. 2 is an elevational view, partially in section, depicting the apparatus of the invention incorporated in the FIG. 1 printing machine with the cover member pivoted to an intermediate position;

FIG. 3 is a sectional elevational view of one embodiment of the illuminating means incorporated in the present invention; and

FIG. 4 is a sectional elevational view of another embodiment of the illuminating means incorporated within the present invention. I 7

While the present invention will be described in connection with a preferred embodiment,.it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of the disclosed electrophotographic printing machine, in which the present invention may be incorporated, continued reference is had to the drawings wherein like reference numerals have been used throughout to designate like elements. FIG. 1 schematically illustrates an electrophotographic printing machine used for producing multi-color reproductions from a stationary original, the original being either transparent, translucent or opaque, whether in the form of single sheets, books or three dimensional objects.

As shown in FIG. 1, the electrophotographic printing machine includes a photoconductive member having a rotatably mounted drum 10 with a photoconductive surface 12 thereon. Drum 10 is mounted on a shaft journaled in a frame (not shown) to rotate in the direction indicated by arrow 14. This moves photoconductive surface 12 sequentially through a plurality of processing stations A through E, inclusive.

For the purpose of the present disclosure several processing stations in the path of movement of photoconductive surface 12 are described functionally.

Drum 10 initially rotates to charging station A. At charging station A, a corona generating device, indicated generally at 16, charges photoconductive surface 12 to a relatively high substantially uniform potential. Corona generating device 16 is arranged to extend in a generally transverse direction across photoconductive surface 12. Preferably, corona generating device 16 is of the type described in US. Pat. No. 2,778,946 issued to Mayo in 1957.

Drum 10 is next rotated to exposure station B where photoconductive surface 12 is exposed to a color tiltered light image of original document 22. A moving lens system, generally designated by the reference numeral l8, and a color filter mechanism shown generally at 20 are disposed at exposure station B. U.S. Pat. No. 3,062,108 issued toMayo in 1962, describes a typical moving lens system suitable for electrophotographic printing. As shown in FIG. 1, original document 22 is supported stationarily upon support member or transparent viewing platen 24. Transparent viewing platen 24 will be described hereinafter, in greater detail, in conjunction with FIG. 2. Lamp assembly 26 and lens system 18 are moved in a timed relation with drum to scan successive incremental areas of original document 22. In this manner, a flowing light image of original document 22 is recorded on photoconductive surface 12. During exposure, filter mechanism interposes selected color filters into the optical light path. The color filters operate on the light rays passing through lens 18 to create a single color light image which records a single color electrostatic latent image on photoconductive surface 12. The foregoing single color latent image corresponds to a preselected spectral region of the electromagnetic wave spectrum.

After the electrostatic latent image is recorded on photoconductive surface '12, drum 10 rotates to development station C. At development station C, three development units, generally indicated by the reference numerals 28, 30 and 32 are positioned. A suitable development station employing a plurality of development units (in this case three) is disclosed in copending U.S. Pat. application Ser'. No. 255,259 filed in 1972. The development units disclosed therein are magnetic brush development units. Typical magnetic brush development units utilize a magnetizable developer mix which includes carrier granules and toner particles. A directional flux field continually forms a brush of developer mix. This brush of developer mix is brought into contact with the electrostatic latent image recorded on photoconductive surface 12. In this manner, toner particles are attracted electrostatically to the latent image rendering it visible. Development units 28, 30 and 32 respectively, contain discretely colored toner particles. Each of the toner particles contained within the respective development unit corresponds to the complement ofthe single color light image transmitted through filter 20. For example, an electrostatic latent image formed from a green filtered light image is made visible by depositing green absorbing magenta toner particles thereon. Similarly, electrostatic latent images formed from blue and red light images are developed with yellow and cyan toner particles, respectively. It should be noted, however, that during any one cycle, only one toner powder image is developed and transferred to a sheet of final support material 34. Hence, it is apparent that three cycles are required in order to completely transfer each of the respective toner powder images to support material 34.

Drum 10 is now rotated to transfer station D where the powder image adhering electrostatically to photoconductive surface 12 is transferred to final support material 34. A bias transfer roll, shown generally at 36, recirculates sheet 34 and is electrically biased to a potential of sufficient magnitude and polarity to electrostatically attract toner particles from photoconductive surface 12 thereto. A suitable electrically biased transfer roll is described in U.S. Pat. No. 3,612,677 issued to Langdon et al. in 1 971. Transferrol'l'36, preferably, is of the same diameter as drum l0 and rotates at the same speed therewith. Hence, transfer roll 36 rotates in synchronism with photoconductive surface 12. Inasmuch as support material 34 is releasably secured to transfer roll 36 for movement therewith in a recirculating path, successive toner powder images may be transferred thereto in superimposed registration from photoconductive surface 12. As depicted in FIG. 1, transfer roll 36 rotates in the direction indicated by arrow Support material 34 is advanced from stack 40 supported on tray member 42. Feed roll 44, in operative communication with retard roll 46, separates and advances the uppermost sheet from stack 40. The advancing sheet moves into a paper chute 48 and is directed into the nip of register rolls 50. Thereafter, gripper fingers 52, mounted on transfer roll 36 secure releasably thereto support material 34 for movement in a recirculating path. In this manner, successive toner powder images are attracted electrostatically to support material 34 in superimposed registration with one another forming a multi-layered toner powder image corresponding, in color, to the original multi-colored document.

With continued reference to FIG. 1, sheet 34 is stripped from transfer roll 36 and transported on endless conveyor belt 54 to fixing station E where a fuser, indicated generally at 56, coalesces and permanently secures the transferred powder image to sheet 34. A suitable fuser is disclosed in U.S. Pat. No. 3,498,592 issued to Moser et al. in 1970.

After the fixing process, sheet 34 is advanced by endless conveyor belts 58 and 60 to catch tray 62 for subsequent removal therefrom by a machine operator.

The final processing station in the direction of rotation of drum 10, ad indicated by arrow 14, is cleaning station F. U.S. Pat. No. 3,590,412 issued to Gerbasi in 1971 describes a suitable brush cleaning device. As disclosed therein, a rotatably mounted fibrous brush 64 is positioned at cleaning station F and maintained in contact with photoconductive surface 12. Any residual toner particles remaining on photoconductive surface 12 after each transfer operation, are removed therefrom by brush 64.

Referring now to FIG. 2, the apparatus of the present invention is depicted therein in detail. Stationary support member 24, preferably, includes a substantially rectangular transparent member 66, made of glass, which is secured by suitable means to the frame of the electrophotographic printing machine depicted in FIG. 1. Transparent member or platen 66 rests upon resilient means or a soft edge gasket 68 which is secured to the horizontal dependent flange 70 ofthe rigid machine frame. A cover plate 72, affixed to the machine frame is placed thereover and provided with an opening therein to expose the top surface of platen 66.

A cover member or platen cover 74 is mounted pivotably along one edge of support member 24 and includes a substantially rigid continuous outer shell 76 having affixed thereto a resilient sheet member 78 made of an elastomeric material such as a soft rubberlike backing. Resilient sheet member 78 may be fabricated from either a natural rubber or any number of commercially available synthetic rubbers, e.g. foam polyurethane, which is affixed to outer shell 76 by means of a suitable adhesive. Illuminating means, or electroluminescent panel 80 is attached to backing 78 and arranged to contact the upper exposed surface of glass platen 66 when cover member 72 is moved from the opened position to the fully closed position. A handle 82 is provided atthe free end of cover member 74 and provides a means by which cover member 74 can be raised and lowered. To permit cover member 74 to be raised over large objects to be reproduced, such as books, while still permitting cover member 74 to lie in a plane substantially parallel to platen 66, cover mem ber 74 is double hinged. Double hinge 84 is secured to cover member 74 at the end thereof opposed from handle 82. A suitable double hinge is described in US. Pat. No. 3,062,110 issued to Shepardson et al. in 1962.

The present invention further includes sensing means 85 for detecting the position of cover member 74. The sensing means indicates when cover member 74 has pivoted to an intermediate position located between the opened and closed position. The intermediate position is that normally assumed by cover member 72 when a thick object such as a book is disposed upon transparent platen 66. The sensing means may be a switch arranged to activate a suitable circuit included within the machine logic. The activating circuit, in turn, energizes electroluminescent panel 80. Hence, the light from electroluminescent panel 80 discharges photoconductive surface 12 in the border regions thereof preventing its development. Electroluminescent panel 80 will be described, in detail, hereinafter with reference to FIGS. 3 and 4.

FIG. 3 describes one embodiment of the electroluminescent panel and FIG. 4 describes another embodiment thereof. In conventional electroluminescent panels, a layer of luminescent material is interposed between a pair of electrodes and the combination deposited upon a substrate. Generally, the electroluminescent material is made of phosphors which give off light when an alternating electric field is applied to the electrodes. One embodiment of an electroluminescent panel suitable for use with the present invention is depicted in FIG. 3.The electroluminescent panel depicted therein is termed a ceramic electroluminescent panel. As shown therein, the panel includes a base metal plate 86 having a ceramic enamel ground coat layer 88 deposited thereon. The active layers thereof adhere to base metal 86. A dielectric 90 such as a barium titanite type enamel layer is deposited over the ceramic ground coat 88. Phosphor layer 92, which is composed of a phosphor embedded in another ceramic enamel layer, is deposited over dielectric 90. A trans parent conductor 94, preferably a glass having a tin oxide coating thereon, e.g. such a glass is made by Pittsburgh Plate Glass Company under the trademark NESA, is adhered to phosphor layer 92. A clear ceramic moisture barrier 96 is affixed to transparent electrode 94. Moisture barrier 96 is used to prevent water molecules from contaminating phosphor layer 92. In operation. current generating means 99 develops an alternating current which passes from base plate 96 through ceramic ground coat 88, dielectric 90 and phosphor 92 to transparent electrode 94. This current excites phosphor layer 92 resulting in its emitting light.

An alternate embodiment of electroluminescent panel 80 is illustrated schematically in FIG. 4. The a1- ternate type of electroluminescent panel of FIG. 4 is made ofa plastic. The construction is somewhat similar to the ceramic panel shown in FIG. 3. As illustrated in FIG. 4, an aluminum foil conductor. 98 has a dielectric layer 100 deposited thereon. Dielectric layer 100 may be a layer of barium .titanite embedded in plastic. A phosphor layer 102, which is also embedded in a layer of plastic, is deposited on dielectric 100. Transparent electrode 104 is secured to phosphor layer 102. Preferably, transparent electrode 104 is a fiber glass paper impregnated with indium to make it conductive. When this fiber glass paper is applied to a wet phosphor and an organic binder surface, it becomes completely transparent. As in the case of the ceramic panel depicted in FIG. 3, there is a clear moisture barrier I06 sandwiched about the entire panel to prevent moisture particles from contaminating phosphor 102. Moisture barrier 106 is, in this case, plastic. The electroluminescent panel depicted in FIG. 4 is also activated by applying an alternating current from current source 108 across aluminum conductor 98 through dielectric and phosphor 102 to transparent conductor 104. In this way, phosphor layer 102 is excited and emits light rays therefrom.

The electroluminescent phosphor is basically a zinc sulfide material. The phosphor emits light when placed in an alternating electric field. In the present invention, the phosphor is energized when cover member 74 is disposed at the intermediate position. This is sensed by a suitable detector or switch. Thereupon, circuit means associated with the machine logic activate an alternating current source which causes the phosphor to luminesce. In this manner, the border regions surrounding the original document are illuminated. The light rays therefrom are focused onto photoconductive surface 12 discharging the charge in the border regions. The discharged region of photoconductive surface 12 does not attract toner particles, and the border region remains undeveloped. Hence, the border regions surrounding the image remain the color of the original support material and do not have any toner particles deposited thereon.

Thus, it is apparent that there has been provided, in accordance with the present invention, an apparatus for housing an original document that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.

What is claimed is:

1. An electrophotographic printing machine of the type having a corona generating device for charging a photoconductive surface to a substantially uniform potential, and an exposure mechanism for creating a light image of an original document arranged to be recorded on the photoconductive surface, wherein the improvement includes:

a support member mounted on the printing machine, said support member being arranged to hold the original document in a light projecting relationship with the exposure mechanism for recording the light image thereof on the photoconductive surface;

a cover member operatively associated with said support member, said cover member being movable from an opened position permitting the original document to be disposed on said support member to a closed position securing releasably thereto the original document; and

means for illuminating the original document and the marginal portion of said support member extending beyond the original document to discharge the photoconductive surface in the marginal portion and prevent the development thereof, said illuminating means being affixed to said cover member and arranged to contact the original document disposed in said support member.

2. A printing machine as recited in claim 1, further including:

means for sensing that said cover member moved from the opened position to a predetermined position intermediate the opened position and the closed position; and

means, responsive to said sensing means indicating said cover member being substantially at about the predetermined position, for energizing said illuminating means.

3. A printing machine as recited in claim 1, wherein said support member includes:

a substantially rigid frame member secured to the printing machine said frame member having an aperture therein;

resilient means secured to said frame member on the periphery of the aperture therein; and

a transparent member having a generally planar surface, said transparent member being mounted on said resilient means in the aperture of said frame member permitting light rays to be transmitted therethrough. 4. A printing machine as recited in claim 1, wherein said cover member includes:

a substantially rigid outer shell; and a resilient sheet member secured to said outer shell,

said resilient sheet member being interposed between said outer shell and said illuminating means. 5. A printing machine as recited in claim 4, wherein said illuminating means includes an electroluminescent panel affixed to said resilient sheet.

6. A printing machine as recited in claim 5, wherein said electroluminescent panel includes: a transparent electrode; a layer of electroluminescent material overlying said transparent electrode; a layer of dielectric material overlying said electroluminescent material; a layer of conducting material overlying said dielectric material; and means for generating an excitation current passing from said transparent electrode through said electroluminescent material and said dielectric material to said conducting material causing said electroluminescent material to luminesce. 

1. An electrophotographic printing machine of the type having a corona generating device for charging a photoconductive surface to a substantially uniform potential, and an exposure mechanism for creating a light image of an original document arranged to be recorded on the photoconductive surface, wherein the improvement includes: a support member mounted on the printing machine, said support member being arranged to hold the original document in a light projecting relationship with the exposure mechanism for recording the light image thereof on the photoconductive surface; a cover member operatively associated with said support member, said cover member being movable from an opened position permitting the original document to be disposed on said support member to a closed position securing releasably thereto the original document; and means for illuminating the original document and the marginal portion of said support member extending beyond the original document to discharge the photoconductive surface in the marginal portion and prevent the development thereof, said illuminating means being affixed to said cover member and arranged to contact the original document disposed in said support member.
 2. A printing machine as recited in claim 1, further including: means for sensing that said cover member moved from the opened position to a predetermined position intermediate the opened position and the closed position; and means, responsive to said sensing means indicating said cover member being substantially at about the predetermined position, for energizing said illuminating means.
 3. A printing machine as recited in claim 1, wherein said support member includes: a substantially rigid frame member secured to the printing machine, said frame member having an aperture therein; resilient means secured to said frame member on the periphery of the aperture therein; and a transparent member having a generally planar surface, said transparent member being mounted on said resilient means in the aperture of said frame member permitting light rays to be transmitted therethrough.
 4. A printing machine as recited in claim 1, wherein said cover member includes: a substantially rigid outer shell; and a resilient sheet member secured to said outer shell, said resilient sheet member being interposed between said outer shell and said illuminating means.
 5. A printing machine as recited in claim 4, wherein said illuminating means includes an electroluminescent panel affixed to said resilient sheet.
 6. A printing machine as recited in claim 5, wherein said electroluminescent panel includes: a transparent electrode; a layer of electroluminescent material overlying said transparent electrode; a layer of dielectric material overlying said electroluminescent material; a layer of conducting material overlying said dielectric material; and means for generating an excitation current passing from said transparent electrode through said electroluminescent material and said dielectric material to said conducting material causing said electroluminescent material to luminesce. 